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31.
N.P. Ferreira J.A. Strauss H.G.C. Human 《Spectrochimica Acta Part B: Atomic Spectroscopy》1982,37(4):273-279
The absorbance by metastable argon atoms of the Ar 696.543 nm line in the modified Grimm-type electrical discharge source was measured at different discharge conditions and at distances varying from 0.25 to 6 mm from the cathode. A uranium/argon hollow cathode lamp was used as primary source, which gave an argon gas temperature of 850 K when run at 12 mA. A maximum absorbance of 0.57 was found 3 mm from the cathode at 600 V, 80 mA. The magnitude of absorbance increases with discharge current while the position of maximum absorbance shifts away from the cathode with increase in discharge voltage. The quenching of metastable atoms by nitrogen is demonstrated.The spatial distribution of the intensity of four different types of spectral lines is shown. The approximate number densities of the different particles are 1012cm?3 for metastable argon atoms, 1016cm?3 for neutral argon atoms, 1013 cm?3 for sputtered copper atoms and 1014cm?3for electrons. 相似文献
32.
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34.
M.?BeyerEmail author S.?Strauss P.?Schuck S.?A.?Sofianos 《The European Physical Journal A - Hadrons and Nuclei》2004,22(2):261-269
We investigate properties and the distribution of light nuclei (
) in symmetric nuclear matter of finite temperature within a microscopic framework. For this purpose we have solved few-body Alt-Grassberger-Sandhas-type equations for quasi-nucleons that include self-energy corrections and Pauli blocking in a systematic way. In a statistical model we find a significant influence in the composition of nuclear matter if medium effects are included in the microscopic calculation of nuclei. If multiplicities are frozen out at a certain time (or volume), we expect significant consequences for the formation of light fragments in a heavy ion collision. As a consequence of the systematic inclusion of medium effects, the ordering of multiplicities becomes opposite to the law-of-mass action of ideal components. This is necessary to explain the large abundance of
-particles in a heavy ion collision that are otherwise largely suppressed in an ideal equilibrium scenario.PACS:
25.70.-z Low and intermediate energy heavy-ion reactions - 25.70.Pq Multifragment emission and correlations - 21.65. + f Nuclear matter - 21.45. + v Few-body systems 相似文献
35.
Higham LT Kreher UP Mulder RJ Strauss CR Scott JL 《Chemical communications (Cambridge, England)》2004,(20):2264-2265
A member of a new class of novel macrocycles possessing both polyether and phenolic functionalities, forms dimers in both the solid-state and in solution when exposed to chloroform, dichloromethane or toluene, but does not self-associate in the presence of dimethyl sulfoxide. 相似文献
36.
[reaction: see text] Aryl alpha,beta-unsaturated ketones and aldehydes were synthesized, in moderate to excellent yields, with use of dimethylammonium dimethyl carbamate (DIMCARB) as a recyclable reaction medium and as a catalyst. 相似文献
37.
Singh JB Sirotenko V Slattery P Smith E Smith RP Snihur R Snow GR Snow J Snyder S Solomon J Sorin V Sosebee M Sotnikova N Soustruznik K Souza M Stanton NR Steinbruck G Stephens RW Stevenson ML Stichelbaut F Stoker D Stolin V Stoyanova DA Strauss M Streets K Strovink M 《Physical review letters》2000,85(24):5068-5073
Bottom-quark production in &pmacr;p collisions at sqrt[s] = 1.8 TeV is studied with 5 pb(-1) of data collected in 1995 by the D0 detector at the Fermilab Tevatron Collider. The differential production cross section for b jets in the central rapidity region ( | y(b)|<1) as a function of jet transverse energy is extracted from a muon-tagged jet sample. Within experimental and theoretical uncertainties, D0 results are found to be higher than, but compatible with, next-to-leading-order QCD predictions. 相似文献
38.
Song XF Sorin V Sosebee M Sotnikova N Souza M Stanton NR Steinbruck G Stephens RW Stevenson ML Stichelbaut F Stoker D Stolin V Stoyanova DA Strauss M Streets K Strovink M Stutte L Sznajder A Tarazi J Taylor W Tentindo-Repond S Thomas TL Thompson J Toback D Trippe TG Turcot AS 《Physical review letters》2000,85(2):256-261
The D0 collaboration has performed a study of spin correlation in t&tmacr; production for the process t&tmacr;-->bW(+)&bmacr;W-, where the W bosons decay to enu or &mgr;nu. A sample of six events was collected during an exposure of the D0 detector to an integrated luminosity of approximately 125 pb(-1) of sqrt[s] = 1.8 TeV p&pmacr; collisions. The standard model (SM) predicts that the short lifetime of the top quark ensures the transmission of any spin information at production to the t&tmacr; decay products. The degree of spin correlation is characterized by a correlation coefficient kappa. We find that kappa>-0.25 at the 68% confidence level, in agreement with the SM prediction of kappa = 0.88. 相似文献
39.
We investigate when the set of finite products of distinct terms of a sequence 〈x
n
〉
n=1∞ in a semigroup (S,⋅) is large in any of several standard notions of largeness. These include piecewise syndetic, central, syndetic, central*, and IP*. In the case of a “nice” sequence in (S,⋅)=(ℕ,+) one has that FS(〈x
n
〉
n=1∞) has any or all of the first three properties if and only if {x
n+1−∑
t=1
n
x
t
:n∈ℕ} is bounded from above.
N. Hindman acknowledges support received from the National Science Foundation via Grant DMS-0554803. 相似文献
40.
This study is concerned with the derivation of conservation laws of both conservative and non-coaservative dynaraical systems with finite numbers of degrees of freedom. First, the derivation of generators of the infinitesimal transformations of the generalized coordinates and time from Noether's basic identity is discussed. In the second part, a special class of conservation laws of conservative dynamical systems which are called action integral conservation laws is developed. 相似文献